MOSCOW -- The Soviet Union bankrolled terrorism on a wide scale, including giving arms and munitions to Palestinian extremists to kill Americans and Israelis and to sabotage world trade in diamonds and oil, an adviser to President Boris N. Yeltsin said yesterday.

Claiming to have the "smoking gun" proving the Communist Kremlin's long-suspected, but never documented, ties with international terror, Sergei M. Shakhrai, Mr. Yeltsin's top legal adviser, said that impounded Soviet Communist Party documents clearly showed that the party covertly aided "several dozen" foreign countries and organizations, among them the Popular Front for the Liberation of Palestine.

Mr. Shakhrai made the disclosure on the eve of a hearing by the Russian Constitutional Court, which convenes today to determine whether Mr. Yeltsin overstepped his powers last year by halting Communist Party activities and then banning the once-omnipotent force in Soviet life altogether.

During recent months, leaked or declassified documents from seized party archives have shown how Soviet Communists shamelessly appropriated government funds to finance their comrades abroad -- including a $15 million payment reportedly made to the Communist Party U.S.A.

But Mr. Shakhrai's statements at a news conference were the most unequivocal yet to sketch the ties between Moscow and foreign terrorists.

Since the demise of the East-West divide, tight connections have already been proven between some former Soviet satellites such as East Germany and acts of terrorism directed against Western democracies.

Mr. Shakhrai offered only one detailed example of the Kremlin's involvement, but it concerned one of the most extreme of the Palestinian groups, the Popular Front for the Liberation of Palestine, led by Dr. George Habash, a physician.

Reading to reporters from a document taken from the Soviet Communist Party's so-called "Special File," dated May 16, 1975, Mr. Shakhrai said that two days earlier, on May 14, the KGB, on orders from the party Central Committee, handed over "foreign-made arms and ammunition" to leaders of the Popular Front's External Operations Service.

The non-Soviet origin of the weapons would have meant they could not be traced to Moscow. Moreover, the document, stamped "top secret," left no doubts that the Soviets expected the arms to be used for political violence.

The "chief goal" of the deal, the document quoted by Mr. Shakhrai said, was "the continuation by special means of the oil war; actions against American and Israeli personnel in third countries; sabotage and terrorism, sabotage against the 'diamond trust,' " he read.

"All these are in the Central Committee's documents, and everything will be published when the time comes," Mr. Shakhrai said, waving the document at reporters.

He refused to give journalists additional examples but indicated that the Irish Republican Army might have been another recipient of Soviet funds.

Where and when the PFLP, a Marxist group, used the arms and ammunition provided by the KGB was not immediately clear. But theoretically, they could have been used in one of the group's most spectacular operations: the June 1976 hijacking of an Air France jetliner to Entebbe, Uganda.

At the time it aided the PFLP, the Communist Party, led by General Secretary Leonid I. Brezhnev, was still officially espousing a policy of detente with the West. In his role as party leader, Mr. Brezhnev would ordinarily have chaired sessions of the Central Committee.

By trying to disrupt the international trade in petroleum, the Kremlin may have hoped to hamstring the West's economy and win higher prices for its own oil exports. Similarly, the Soviet Union is a large producer of diamonds.

"In principle, the money for terrorist organizations was transferred through the same channel as assistance to foreign Communist parties," Mr. Shakhrai said.

"In general, a phone call from the Politburo [the party's leading organ] was enough for the Foreign Trade Bank to allocate a certain sum of money," he said. "A KGB officer would collect it and write a receipt, all of which can now be found in the special Politburo folder."

Although Mr. Shakhrai just resigned as Mr. Yeltsin's legal counselor, he was named by the president yesterday to be among those who plead Mr. Yeltsin's cause before the Constitutional Court.

The trial should provide an unprecedented examination of the activities of the Communist Party since it seized power in Russia in 1917. Mr. Yeltsin was quoted yesterday by the Itar-Tass news agency as saying that society now demands to know the "whole truth" about the party and its responsibility for dragging Soviet society into the "deepest of economic and moral-political crises."